75 research outputs found
Extinction of Taurus, Orion, Perseus and California Molecular Clouds Based on the LAMOST, 2MASS and Gaia surveys I: Three-dimensional Extinction and Structure
The three-dimensional extinction and structure are studied for the Taurus,
Orion, Perseus and California molecular clouds based on the LAMOST
spectroscopy. Stellar color excess is calculated with the intrinsic color index
derived from the atmospheric parameters in the LAMOST DR8 catalog and the
observed color index in the Gaia EDR3 and the 2MASS PSC. In combination with
the distance from the Gaia EDR3 parallax, the three-dimensional dust extinction
maps are retrieved in the color excesses and
with an uncertainty of 0.03mag and 0.07mag
respectively. The extinction maps successfully separate the clouds that overlap
in the sky area and manifest the structure of the individual cloud. Meanwhile,
a bow-like structure is found with a distance range from 175pc to 250pc, half
of which is a part of the Per-Tau Shell in similar coordinates and distance
while the other half is not. Three low-extinction rings are additionally
discovered and briefly discussed.Comment: 22 pages, 15 figures, 2 tables, accepted for publication in Ap
SPar: estimating stellar parameters from multi-band photometries with empirical stellar libraries
Modern large-scale photometric surveys have provided us with multi-band
photometries of billions of stars. Determining the stellar atmospheric
parameters, such as the effective temperature (\teff) and metallicities (\feh),
absolute magnitudes (), distances () and reddening values (\ebr) is
fundamental to study the stellar populations, structure, kinematics and
chemistry of the Galaxy. This work constructed an empirical stellar library
which maps the stellar parameters to multi-band photometries from a dataset
with Gaia parallaxes, LAMOST atmospheric parameters, and optical to
near-infrared photometry from several photometric surveys. Based on the stellar
library, we developed a new algorithm, SPar (\textbf{S}tellar
\textbf{P}arameters from multib\textbf{a}nd photomet\textbf{r}y), which fits
the multi-band stellar photometries to derive the stellar parameters (\teff,
\feh, , and \ebr) of the individual stars. The algorithm is applied to
the multi-band photometric measurements of a sample of stars selected from the
SMSS survey, which have stellar parameters derived from the spectroscopic
surveys. The stellar parameters derived from multi-band photometries by our
algorithm are in good agreement with those from the spectroscopic surveys. The
typical differences between our results and the literature values are 170\,K
for \teff, 0.23\,dex for \feh, 0.13\,mag for and 0.05\,mag for \ebr. The
algorithm proved to be robust and effective and will be applied to the data of
future large-scale photometric surveys such as the Mephisto and CSST surveys.Comment: 16 pages, 10 figures, Accepted by The Astronomical Journal on
7/8/202
A Dual-spine Approach to Load Error Repair in a HEMS Sensor Network
In a home energy management system (HEMS), appliances are becoming diversified and intelligent, so that certain simple maintenance work can be completed by appliances themselves. During the measurement, collection and transmission of electricity load data in a HEMS sensor network, however, problems can be caused on the data due to faulty sensing processes and/or lost links, etc. In order to ensure the quality of retrieved load data, different solutions have been presented, but suffered from low recognition rates and high complexity. In this paper, a validation and repair method is presented to detect potential failures and errors in a domestic energy management system, which can then recover determined load errors and losses. A Kernel Extreme Learning Machine (K-ELM) based model has been employed with a Radial Basis Function (RBF) and optimised parameters for verification and recognition; whilst a Dual-spline method is presented to repair missing load data. According to the experiment results, the method outperforms the traditional B-spline and Cubic-spline methods and can effectively deal with unexpected data losses and errors under variant loss rates in a practical home environment
A Survey of Lower Limb Rehabilitation Systems and Algorithms Based on Functional Electrical Stimulation
Functional electrical stimulation is a method of repairing a dysfunctional limb in a stroke patient by using low-intensity electrical stimulation. Currently, it is widely used in smart medical treatment for limb rehabilitation in stroke patients. In this paper, the development of FES systems is sorted out and analyzed in a time order. Then, the progress of functional electrical stimulation in the field of rehabilitation is reviewed in details in two aspects, i.e., system development and algorithm progress. In the system aspect, the development of the first FES control and stimulation system, the core of the lower limb-based neuroprosthesis system and the system based on brain-computer interface are introduced. The algorithm optimization for control strategy is introduced in the algorithm. Asynchronous stimulation to prolong the function time of the lower limbs and a method to improve the robustness of knee joint modeling using neural networks. Representative applications in each of these aspects have been investigated and analyzed
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Intracellular Imaging with Genetically Encoded RNA-Based Molecular Sensors
Abstract Genetically encodable sensors have been widely used in the detection of intracellular molecules ranging from metal ions and metabolites to nucleic acids and proteins. These biosensors are capable of monitoring in real-time the cellular levels, locations, and cell-to-cell variations of the target compounds in living systems. Traditionally, the majority of these sensors have been developed based on fluorescent proteins. As an exciting alternative, genetically encoded RNA-based molecular sensors (GERMS) have emerged over the past few years for the intracellular imaging and detection of various biological targets. In view of their ability for the general detection of a wide range of target analytes, and the modular and simple design principle, GERMS are becoming a popular choice for intracellular analysis. In this review, we summarize different design principles of GERMS based on various RNA recognition modules, transducer modules, and reporting systems. Some recent advances in the application of GERMS for intracellular imaging are also discussed. With further improvement in biostability, sensitivity, and robustness, GERMS can potentially be widely used in cell biology and biotechnology
An Auto-Calibration Approach to Robust and Secure Usage of Accelerometers for Human Motion Analysis in FES Therapies
A Functional Electrical stimulation (FES) therapy is a common rehabilitation intervention after stroke, and finite state machine (FSM) has proven to be an effective and intuitive FES control method. The FSM uses the data information generated by the accelerometer to robustly trigger state transitions. In the medical field, it is necessary to obtain highly safe and accurate acceleration data. In order to ensure the accuracy of the acceleration sensor data without affecting the accuracy of the motion analysis, we need to perform acceleration big data calibration. In this context, we propose a method for robustly calculating the auto-calibration gain using redundant acceleration vectors, and then calibrating the data generated by the accelerometer based on the calculated gain. The selection of the acceleration vector involved in the gain calculation is demonstrated by different experiments. The results show that the auto-calibration gain calculated after calibration is very close to 1, and the error is significantly less than before calibration, which indicates that the accelerometer unit is well calibrated
The measurement of masses of OB-type stars from LAMOST DR5
The measurements of masses and luminosities of massive stars play an
important role in understanding the formation and evolution of their host
galaxies. In this work, we present the measurement of masses and luminosities
of 2,946 OB-type stars, including 78 O-type stars and 2,868 B-type stars, based
on their stellar parameters (effective temperature, surface gravity, and
metallicity) and PARSEC isochrones model. Our results show that the median mass
and luminosity of the 2,946 OB-type stars are 5.4 M and
log(L/L)=3.2 with the median relative error of 21.4 and 71.1,
respectively. A good agreement between our results estimated by using our
method and those derived by using the orbital motions of binary stars from the
literature is found for some B-type stars. In addition, we also fit the
mass-luminosity relation of B-type stars by using our derived mass and the
luminosity from DR3.Comment: 12 pages, 10 figures, 1 table, accepted for publication in ApJ
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Imaging and detecting intercellular tensile forces in spheroids and embryoid bodies using lipid-modified DNA probes
Cells continuously experience and respond to different physical forces that are used to regulate their physiology and functions. Our ability to measure these mechanical cues is essential for understanding the bases of various mechanosensing and mechanotransduction processes. While multiple strategies have been developed to study mechanical forces within two-dimensional (2D) cell culture monolayers, the force measurement at cell-cell junctions in real three-dimensional (3D) cell models is still pretty rare. Considering that in real biological systems, cells are exposed to forces from 3D directions, measuring these molecular forces in their native environment is thus highly critical for the better understanding of different development and disease processes. We have recently developed a type of DNA-based molecular probe for measuring intercellular tensile forces in 2D cell models. Herein, we will report the further development and first-time usage of these molecular tension probes to visualize and detect mechanical forces within 3D spheroids and embryoid bodies (EBs). These probes can spontaneously anchor onto live cell membranes via the attached lipid moieties. By varying the concentrations of these DNA probes and their incubation time, we have first characterized the kinetics and efficiency of probe penetration and loading onto tumor spheroids and stem cell EBs of different sizes. After optimization, we have further imaged and measured E-cadherin-mediated forces in these 3D spheroids and EBs for the first time. Our results indicated that these DNA-based molecular tension probes can be used to study the spatiotemporal distributions of target mechanotransduction processes. These powerful imaging tools may be potentially applied to fill the gap between ongoing research of biomechanics in 2D systems and that in real 3D cell complexes
Identification of Blue Horizontal-Branch Stars From LAMOST DR5
We construct a new catalog of the blue horizontal-branch (BHB) stars from the
Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) DR5 dataset,
which contains 5355+81 BHB stars at high Galactic latitude
((). We combine the spectral line indices with a set of
Balmer line profile selection criteria to identify the BHB stars. During the
selection process, we use the line index of \ion{Ca}{2}\,K to exclude the
metal-rich A-type dwarfs. We obtain their atmospheric parameters by
cross-matching our BHB stars with the catalog provided by \citet{Xiang2022}.
The results show that our sample is consistent with the theoretical -log\, evolutionary tracks of the BHB stars, indicating that our method
is robust for identifying BHB stars from the LAMOST spectra. Their spatial
distribution indicates that most of our BHB stars are located in the inner halo
or the disk of the Milky Way. Combined with other BHB samples from the
literature, the BHB stars can cover a large Galactic volume, which makes it a
better probe for studying the kinematics, dynamics, and structural
characteristics of the Milky Way.Comment: accepted by ApJS.15 pages, 18 figure
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